Differential pump



c. E. ANDERSON DIFFERENTIAL PUMP sp d June 25, 1924 May 26, 1925.

IN V EN TOR.

' ATTORNEYS Patented May 26, 1925.

UNITED STATES v 1,539,289 PATENT OFFICE.

CARL E, ANDERSON, OF BROO'KLYN, NEW YORK, ASSIGNOR T AMERIC'AN MACHINE & FOUNDRY COMPANY, A CORPORATION OF NEW JERSEY.

DIFFERENTIAL PUMP.

Application filed June 25, 1924. Serial N9. 722,208.

To all whom it may concern:

Be it known that I, CARL E. ANDERSON, a citizen of the United States, residing at Brooklyn, county of Kings, and State of New York, have invented a new and useful Improvement in Differential Pumps, of which the following is a specification.

This invention relates to a differential pump, the purpose of which is to deliver an extremely. small quantity of liquid at high pressure, said quantity being far below that delivered by the smallest ordinary pump which it is practicable to construct. \Vith this and other objects not specifically mentioned in view, the invention consists in certain constructions and combinations which will be hereinafter fully described and then specifically set forthiin the claims hereunto appended.

In the accompanying drawings, which form a part of this specification and in which like characters of reference indicate the same or like parts, Fig. 1 is a central sectional elevation of a pump constructed in accordance with the invention; Fig. 2 is a composite view of transverse vertical cross sections of the rotors and housings of the pump shown in Fig. 1, the view being taken at the lines 2-2 and 22, Fig. 1, and looking from the centre of the housing toward each end; and Fig. 3 is a horizontal cross section of the housing at the shaft centre at 33 in Fig. 1.

In carrying the invention into effect, there is provided two cylinders having capacities which differ in accordance with the required outflow; means for circulating liquid from the larger cylinder through the smaller cylinder, discharging the excess which of course depends upon the relative capacities of the two cylinders, and returning the remainder to the larger cylinder; and means for supplying additional liquid to the larger cylinder during a succeeding cycle of operations to replace the excess liquid discharged, so that the pump can be of practicable size and yet deliver an extremely small quantity of 'liquid. In the best constructions, the cylinders are of like bore but of diiferentlengths; the circulating mecha nism includes vaned rotors of a well known type eccentrically operating in said cylinders, a conduit leading from the dischargeside of the larger cylinder to the suction side of the smaller cylinder and to the out let of the pump, a conduit leading from the discharge side of the smaller cylinder to the suction side of the larger cylinder, and said means includes a suction conduit leading to the larger cylinder. The foregoing parts may be widely varied in construction within the scope of the claims, for the particular device selected to illustrate the invention is but one of many possible concrete embodiments of the same. The invention therefore is not to be restricted to the precise details of the structure shown and described.

Referring to the drawings, 4 indicates a supporting casting for the pump having a wall 5 separating a cylinder 6 from a cylinder 7, these cylinders being of like bore and having a common axis but being of different lengths, the cylinder 6 being the longer and therefore being the larger-in point of capacityof the two. Located in the larger cylinder 6 is a rotor 8 having a vane 9 pivoted thereto. Similarly. a rotor 10 having a vane 11 is located in the cylinder 7. These rotors are respectively mounted on oppositely disposed eccentrics 12 and 13 formed on a shaft 14 which is journaled in suitable hearings in removable heads 15 and 16, respectively closing the outer ends of the cylinders 6 and-7. This shaft derives its motion from any suitable source not shown.

Th casting a is provided with a suction conduit 17 leading to the suction side of the cylinder 6. The rotors of the shaft, with its eccentrics, form a part of mechanism for circulating liquid from the larger cylinder through the smaller cylinder, discharging the excess liquid, and returning the remainder to the larger cylinder. This mechanism further includes a conduit 18 leading from the discharge side of the larger cylinder to the suction side of the smaller cylinder and to the outlet 19 of the pump. Said meclianism further includes a conduit 20 leading from the discharge side of the smaller cyl- 'inder to the suction side of the larger cylinder at the same pointwhere the suction conduitl'? enters the same.

The operation of the device is asfollows: Assuming that the suction conduit 17 is in communication -with a suitable source of liquid supply, that the pump is primed or full of liquid, and that back pressure exists at the pump outlet 19,-n1ovement of the rotor 8 in the cylinder 6, in the direction of the arrow, will force the liquid in that cylinder into the conduit 18 which is open to both cylinders and to the outlet 19. The back pressure at 19 will then cause the liquid flowing into the conduit 18 to enter the cylinder 7 at its suction side and flow thereinto to its capacity. \Vhen the cylinder 7 is full, however, there is an excess of liquid in the conduit 18 due to the difference in the capacities of the two cylinders, and this excess, however small, is forced out through the pump outlet 19. The liquid which has thus entered the cylinder 7, is forced by the rotor 10 into the return conduit 20, which conducts it back to the suction side of the larger cylinder 6 where it is again acted upon by the rotor 8. But since a small quantity of the liquid circulating from the larger cylinder toward the smaller cylinder was discharged through thepump outlet 19, it is necessary that additional liquid be supplied to the larger cylinder to replace the excess liquid discharged, in order that during its second cycle of operations the larger cylinder may be full of liquid] To this end, the conduit 20 enters the suction side of the cylinder 6 where the suction conduit 17 enters the same. The additional liquid required is therefore drawn through the suction conduit 17.

The pump is of a size equal to the smallestsize it is practicable to construct for commercial purposes, so that it will be durable as well as eflicient for the particular purpose intended. Its high efficiency for the purpose intended is due to the fact that the pump constantly circulates a volume ofliquid which is many times as great as that required for discharge, so that any loss due to leakage is applied to the relatively great volume of circulating liquid, without affecting the relatively small quantity discharged. The volum of liquid delivered, being controlled by the differential capacity of the two cylinders, may be widely varied in different pumps of the same size by simply varying the relative lengths of the cylinders and rotors and eccentrics therein, without changing the. angular velocity of the shaft ll, so that a large number of pumps of this type having different capacities may be directly connected with like high speed electric motors, thus standardizing the units.

hat is claimed is:

1. A differential pump, comprising two cylinders having capacities which differ in accordance with the required outflow, mechanism for circulating liquid from the larger cylinder through the smaller cylinder, discharging the excess liquid, and returning the remainder to the larger cylinder, and means for supplying additional liquid to the larger cylinder to replace the excess liquid discharged.

2. A difierential pump, comprising two cylinders having capacities which differ in accordance with the required outflow, mechanism for circulating liquid from the lar er cylinder through the smaller cylinder, ischarging the excess liquid, and returning the remainder to the larger cylinder, and means for supplying additional liquid to the larger cylinder to replace the excess liquid discharged, said cylinders being of like bone but of different lengths.

3. A differential pump, comprising two cylinders having capacities which differ in accordance with the required outflow, mechanism for circulating liquid from the larger cylinder through the smaller cylinder, discharging the excess liquid, and returning the remainder to the larger cylinder, and means for supplying additional liquid to the larger cylinder to replace the excess liquid discharged, said cylinders being oppositely bored in a supporting casting having a wall separating said cylinders and being provided with removable heads.

4. A-differential pump, comprising two cylinders having capacities which differ in accordance with the required outflow, mechanism for circulating liquid from the larger cylinder through the smaller cylinder, discharging the excess liquid, and returning the remainder to the larger cylinder, and means for supplying additional liquid to the larger cylinder to replace the excess liquid discharged, said mechanism including vaned rotors eccentrically operating in said cylinders.

5. A differential pump, comprising two cylinders having capacities which differ in accordance with the required outflow, mechanism for circulating liquid from the larger cylinder through the smaller cylinder, discharging the excess liquid, and returning the remainder to the larger cylinder, and means for supplying additional liquid to the larger cylinder to replace the excess liquid discharged, said mechanism including vaned rotors, and a shaft having oppositely disposed eccentrics carrying said rotors.

6. A differential pump, comprisin two cylinders having capacities which di er in accordance with the required outflow, mechanism for circulating liquid from the larger cylinder through the smaller cylinder, discharging the excess liquid, and returning the remainder to the larger cylinder, and means for supplying additional liquid to the lar er cylinder to replace the excess liquid ischarged, said mechanism including a conduit leading from the discharge side of the larger cylinder to the suction side of the smaller cylinder and to the outlet of the pump.

7. A differential pump, comprisin two cylinders having capacities which di er in accordance with the required outflow, mechanism for circulating liquid from the larger cylinder through the smaller cylinder, discharging the excess liquid, and returning the v for supplying additional I larger cylinder to replace the excess liquid remainderto the larger cylinder, and means iquid to the larger cylinder to replace the excess liquid disc arged, said mechanism includin a conduit leading from the discharge si e of the smaller c linder'to the suction side of the larger cy inder.

8. A differential pump, comprisin two cylinders having capacities which di er in accordance with the required outflow, mechanism for circulating liquid from the lar er cylinder through the smaller cylinder, charging the excess liquid, and returning the remainder to the larger cylinder, and means for supplying additional liquid to the larger cylinder to replace the excess liquid discharged, said means including a suction conduit leading to the larger cylinder.

9. A difierential pump, comprisin two cylinders having capacities which di er in accordance with the required outflow, mechanism for circulating liquid from the larger cylinder through the smaller cylinder, discharging the excess, liquid, and returning the remainder to thelarger cylinder, and means for supplying additional liquid to the discharged, said mechanism including a conduit leading from the discharge side of the smaller cyhnder to the suction side of the larger cylinder, and said means including a suction conduit leading to the larger cylinder at the same point as the other conduit.

10. A difierential pump, comprisin two cylinders having capacities which di erin accordance with the required outflow, mechanism for circulating liquid from the larger cylinder through the smaller cylinder, discharging the excess liquid, and returning the remainder to the larger-cylinder to replace the excess liquid discharged, said mechanism including vaned rotors, and a shaft having oppositely disposed eccentrics carrying said rotors, said mechanism also including a conduit leadingfrom the dischar e side ofthe larger cylinder to the suction si e of the smaller cylinder and to the outlet of the pump, a conduit leading from the discharge side of the smaller cylinder to the suction side of the larger cylinder, and said means including a suction conduit leading to the larger cylinder.

In testimony whereof, I have signed my name to this specification.

CARL E. ANDERSON. 

